Control device for turbine generators

ABSTRACT

A control device for turbine generators comprising adjustment valve means disposed in a series circuit including a source of elastic fluid (compressible fluid) and a turbine generator driven by fluid supplied from the source so as to control the flow rate of fluid to the turbine; a revolution counter for measuring the number of rotations of the turbine; a circuit for differentiating the output from the revolution counter; a differential amplifier for comparing the output from the differentiation circuit with a preset reference valve and generating a resulting error valve; a second differential amplifier receiving the output of the differentiation circuit and a second reference value and generating an error value and a P.I.D. control circuit receiving the outputs from said differential amplifiers for generating a control output including to control the adjustment valve and in consequence the acceleration of the turbine.

[451 Oct. 17, 1972 CONTROL DEVICE FOR TURBINE GENERATORS PrimaryExaminerG. R. Simmons Attorney-Flynn & Frishauf [72] Inventors: MoritadaKubo; Yasuo Shinomiya,

both of Tokyo, Japan [5 7] ABSTRACT [73] Assignee: Tokyo ShibauraElectric Co., Ltd., Control device for 1 gemajrators P g "j ustmentvalve means disposed In a series circuit m- Kawasakl shi, Japan cludmg asource of elastic fluid (compressible fluid) Flledi Jan. 1971 and aturbine generator driven by fluid supplied from [21] APPL 105,806 thesource so as to control the flow rate of fluid to the turbine; a revoluton counter for measuring the I number of rotations of the turbine; acircuit for dif- [52] US. Cl. ..4l5/36, 318/610, 318/61 1 ferentiatingthe output f the revolution counter; a [51] Int. Cl. ..H02p 9/04differential amplifier for comparing the output from [58] held of Search""318/610, 611; 415/16 the differentiation circuit with apresetreference valve 415/37; 60/10 s; 290/40 41 and generating a resultingerror valve; a second differential amplifier receiving the output of thedif- [56] References cued ferentiation circuit and a second referencevalue and UNITED STATES PATENTS generating an error value and a R.I.D.control circuit receiving the outputs from said differentlal amplifiers3,283,230 11/1966 Davies et al. ..318/61l for generating a comm! outputincluding to control 3,097,488 7/1963 Eggenberger "415/17 X theadjustment valve and' in consequence the accelera- 3,340,883 9/1967Peterne] ..415/l7 X {ion of the turbine 3,291,146 12/1966 Walker..415/17 X 1 2 Claims, 3 Drawing Figures F T 1 150 15 I f 1 fl l P H 1K4i 1 C (o I 15b 4 2 1 I flay G i D l d t 1 'l' I i 13 1 15C 1 (I) K r A 3y I 1 1 1 Z O 1 1 1 N O J 1 I 1 1 15d I 2%!0 L CONTROL DEVICE FORTURBINE GENERATORS .The present invention relates to a control devicefor elastic fluid turbine generators and more particularly to such acontrol device as is also capable of controlling angular acceleration.

With respect to a turbine generator, prevention of mechanical damage dueto fatigue of the materials of the rotary shaft of a generator coupledwith a turbine and other rotating parts such as turbine blades dernandsthat mechanical torque and thermal stress applied to said rotating partsbe constantly controlled. Since there arise sharp changes in themechanical torque and thermal stress applied to the turbine rotorparticularly at its start, it is very important to stabilize the angularspeed change of the rotating parts including that at the start.

However, the conventional method of controlling a turbine generatormainly consists in stabilizing the rotational speed of a turbine, thatis, controlling its angular speed on the basis of an overall controlamount consisting of proportional, integral and differential values,namely, by the P.I.D. system. The angular acceleration of the rotatingparts has only been controlled on the basis of proportional and integralcontrol amounts. Accordingly, the prior art control method isunsatisfactory for full attainment ofthe object of preventing mechanicaldamage to the rotating parts due to the fatigue of their materials.

It is accordingly the object of the present invention to provide acontrol device for turbine generators which is capable of constantlystabilizing the angular speed of the rotor of the turbine generator.

SUMMARY OF THE INVENTION The control device of the present inventioncomprises drawing out by means of a differential amplifier a balancebetween the output from a circuit differentiating the output from aspeed detecting means of the turbine generator and a preset value andusing the output from a control circuit together with the differentiatedvalue of said balance of output in controlling the acceleration of theturbine generator.

A control device for turbine generators according to the presentinvention comprises control valve means disposed in a motive fluid lineincluding a source of elastic fluid (compressible fluid) and a turbinegenerator driven by fluid supplied from the source so as to control theflow rate of fluid to the turbine; a speed detecting means for measuringthe rotational speed of the turbine; a circuit for differentiating theoutput from the speed detecting means; a differential amplifier forcomparing output from the differentiation circuit with a preset valueand drawing out the resulting error value; and a control circuit forgenerating an output including the differentiated value of output fromthe differential amplifier thereby to control the control valve meansand in consequence the acceleration of the turbine.

This invention can be more fully understood from the following detaileddescription when taken in connection with the accompanying drawings, inwhich:

FIG. 1 is a block diagram of a control loop including a control deviceaccording to an embodiment of the present invention;

FIG. 2 is a block diagram of a control circuit associated with thecontrol device of FIG. 1; and

FIG. 3 is a block diagram of a control circuit associated with a controldevice according to another embodiment.

Referring to FIG. 1, numeral 1 denotes a turbine generator whichconsists of a high pressure turbine la, medium pressure turbine 1b, lowpressure turbine 10 and generator 1d, all rotatably fitted to a commonrotary shaft 2. Elastic fluid, for example, steam generated by a boiler3 passes through a closed. loop including control or adjustment valvemeans 4, high pressure turbine 1a, reheater 5, adjustment valve means 6,medium pressure turbine lb and low pressure turbine 10 back to theboiler 3. There are omitted other means which are in practiceincorporated in said closed loop. There is also provided a speeddetector 7 for measuring the rotational speed of the turbine. Output infrom the speed detector 7 is conducted to a control circuit 8, output Zfrom which is in turn supplied as an amount of control to the adjustmentvalve means 4 and 6 which control the volume of steam to be supplied tothe turbine.

The control circuit 8 comprises a differentiation circuit 11 fordifferentiating output to from the revolution counter 7 to generate adifferentiated control amount C 143 (where C is a gain and a is dw/dt asetter 12 for setting a reference value w to the output to and areference value C 03 [where C is a coefficient and a) is (dw/dt) to thedifferentiated control amount C di; a first differential amplifier l3(gain G supplied with w and (n to generate output y a seconddifferential amplifier 14 (gain G supplied with the differentiatedcontrol amount C 11) and the reference value C 03 thereto to produceoutput y,; a proportional controller 15a supplied with said output y togenerate a control amount proportionate to said y,; a differentialcontroller 15b for producing a control amount corresponding to thedifferentiated value of said y,; a proportional controller supplied withsaid output y to generate a control amount proportionate to said-ya; andan integral controller 15d supplied with said output y to produce acontrol amount corresponding to the integrated value of said y Totaloutput Z from these controllers is supplied to the adjustment valves 4and 6.

Output y from the differential amplifier 14 may be expressed as follows:

Y1 2 1 l( )o w/ 1 Output y; from the differential amplifier 13 may beexpressed as follows:

ya z( o 2 Total output from the RID. controller 15 including those fromthe controllers 15a, 15b, 15c and 15d may be expressed as follows:

a it

that is, a control amount for the angular acceleration of the rotor. Inother words, a control amount corresponding to a differentiated value oferrors in the angular acceleration of a turbine also takes part incontrolling its angular speed change, more stabilizing the rotationtorque and thermal stress applied to a turbine than has been possiblewith the prior art.

Another embodiment of the control circuit 8 is presented in FIG. 3.According to this embodiment,

output to from the speed detector 7 is conducted to a primarydifferentiation circuit 17 to obtain a primary differentiated controlamount C rb (where C is a coefficient and a) is dw/dt) and also to asecondary differentiation circuit 18 to obtain a secondarydifferentiated control amount C io (where C is a coefficient and d} is dwldt There is further provided a setter 19 for setting reference valuesm and C ri) [where C is a coefficient and (b is (dw/dt) but C di [whereC, is a coefficient and (ii is (d w/dt to the aforesaid ai C di and'C direspectively. There are also used first, second and third differentialamplifiers 20, 21 and 22 which are supplied with the output C di setvalue C 15 output C 11: set value G rb and output 0) set value (0respectively, thereby to obtain an output representing a balance betweenthe inputs of each group. A total output from these differentialamplifiers 20, 21 and 22 is designated as y and gains therein as G G and6,, respectively.

The P.I.D. controller 24 comprises differential, proportional andintegral controllers 24a, 24b and 24c which are supplied with theaforesaid output y in common to produce total output Z. For briefness,there is omitted the description of the functions of these controllerswhich are the same as those of the preceding embodiment. Said totaloutput Z is conducted to the adjustment valve means 4 and 6. Theaforesaid output y denotes signals of errors with respect to the presetvalue used in operation of a control device according to the presentinvention and is expressed as follows:

The P.l.D. generates the following output derived from the aboveequation 4:

Z=a %+by+cfydt where a, b and c are coefficients.

As seen from FIG. 3, the output y already contains a control amountrelative to the angular speed change to of a turbine and a controlamount corresponding to variations to in said speed change. It will beapparent, therefore, that adjustment of the valve means by said output Zpermits the minute control of the angular speed change of a turbinegenerator, that is, the rotation torque applied to the rotary shaft.

What we claim is:

l. A control device for turbine generators having control valve meansdisposed in a fluid line including a source of elastic fluid and aturbine generator driven by fluid supplied from the source so as tocontrol the feed rate of fluid to the turbine, a speed detecting meansfor measuring the rotational speed of the turbine and a control circuitfor controlling the control valve means and in consequence theacceleration of the turbine as a functio of a co trol output obtained byroce sing th output rom sat speed detecting means: sand contro circuitcomprising:

a first differentiation circuit for differentiating the output (1) fromsaid speed detecting means to generate a first differentiated controlvalue (C m);

a setter for setting a first reference value (w relative to the output(to) from said speed detecting means and a second reference value (C 6relative to the first differentiated control value (C 03);

a first differential amplifier coupled to the output (at) from saidspeed detecting means and supplied with the first reference value (m togenerate an output (Y2);

a second differential amplifier coupled to the output (C ar) of saidfirst differentiation circuit and supplied with the second referencevalue c 03, to generate an output y,; and

a P.l.D. controller including a P.I. controller coupled to the output (yfrom said first differential amplifier and a PD. controller coupled tothe output (y,) from said second differential amplifier and combiningthe outputs from said P.I. and PD. controllers for supplying saidcontrol valve means with a control output.

2. A control device for turbine generators having control valve meansdisposed in a fluid line including a source of elastic fluid and aturbine generator driven by fluid supplied from the source so as tocontrol the feed rate of fluid to the turbine, a speed detecting meansfor measuring the rotational speed of the turbine and a control circuitfor controlling the control valve means and in consequence theacceleration of the turbine as a function of a control output obtainedby processing the output from said speed detecting means, said controlcircuit comprising:

a circuit for generating a primary differentiated control value (C 6)and secondary differentiated control value (Can) of the output (to) fromsaid speed detecting means;

a setter for setting a first reference value (w relative to the output(on) from said speed detecting means, a second reference value (C tbrelative to the primary differentiated control value (C 03) and a thirdreference value (C r'b relative to the secondary differentiated controlvalue (C first, second and third differential amplifiers, said firstdifferential amplifier being coupled to the output (to) of said speeddetecting means and being supplied with said first referencevalue (wsaid second differential amplifier being supplied with said primarydifferentiated control value (C lb) and said second reference value (C63 and said third differential amplifier being supplied with saidsecondary differentiated control value (C io) and said third referencevalue (C 65 and a P.I.D. controller supplied with the outputs (y) fromsaid first, second and third differential amplifiers to generate acontrol output which is coupled to said control valve means.

1. A control device for turbine generators having control valve meansdisposed in a fluid line including a source of elastic fluid and aturbine generator driven by fluid supplied from the source so as tocontrol the feed rate of fluid to the turbine, a speed detecting meansfor measuring the rotational speed of the turbine and a control circuitfor controlling the control valve means and in consequence theacceleration of the turbine as a function of a control output obtainedby processing the output from said speed detecting means, Said controlcircuit comprising: a first differentiation circuit for differentiatingthe output ( omega ) from said speed detecting means to generate a firstdifferentiated control value (C2 omega ); a setter for setting a firstreference value ( omega 0) relative to the output ( omega ) from saidspeed detecting means and a second reference value (C2 omega 0) relativeto the first differentiated control value (C2 omega ); a firstdifferential amplifier coupled to the output ( omega ) from said speeddetecting means and supplied with the first reference value ( omega 0)to generate an output (y2); a second differential amplifier coupled tothe output (C2 omega ) of said first differentiation circuit andsupplied with the second reference value (C2 omega 0) to generate anoutput y1; and a P.I.D. controller including a P.I. controller coupledto the output (y2) from said first differential amplifier and a P.D.controller coupled to the output (y1) from said second differentialamplifier and combining the outputs from said P.I. and P.D. controllersfor supplying said control valve means with a control output.
 2. Acontrol device for turbine generators having control valve meansdisposed in a fluid line including a source of elastic fluid and aturbine generator driven by fluid supplied from the source so as tocontrol the feed rate of fluid to the turbine, a speed detecting meansfor measuring the rotational speed of the turbine and a control circuitfor controlling the control valve means and in consequence theacceleration of the turbine as a function of a control output obtainedby processing the output from said speed detecting means, said controlcircuit comprising: a circuit for generating a primary differentiatedcontrol value (C2 omega ) and secondary differentiated control value (C1omega ) of the output ( omega ) from said speed detecting means; asetter for setting a first reference value ( omega 0) relative to theoutput ( omega ) from said speed detecting means, a second referencevalue (C2 omega 0) relative to the primary differentiated control value(C2 omega ) and a third reference value (C1 omega 0) relative to thesecondary differentiated control value (C1 omega ); first, second andthird differential amplifiers, said first differential amplifier beingcoupled to the output ( omega ) of said speed detecting means and beingsupplied with said first reference value ( omega 0), said seconddifferential amplifier being supplied with said primary differentiatedcontrol value (C2 omega ) and said second reference value (C2 omega 0),and said third differential amplifier being supplied with said secondarydifferentiated control value (C1 omega ) and said third reference value(C1 omega 0); and a P.I.D. controller supplied with the outputs (y) fromsaid first, second and third differential amplifiers to generate acontrol output which is coupled to said control valve means.